The system starts up particularly slowly,Copying data from the SD card is particularly slow.

The entire process of copying data from the SD card takes approximately 8 hours, with the actual SPI interface speed being 2.36 MHz. During the boot phase, copying 150MB of data in sd.c takes only 12 minutes, but during the Linux phase, copying 1.5GB of data takes 8 hours.

The demsg keeps printing.:
[ 667.359240] mmc_spi spi0.0: setup mode 0, 8 bits/w, 1000000 Hz max --> 0
[ 668.383220] mmc_spi spi0.0: setup mode 0, 8 bits/w, 1000000 Hz max --> 0

Start with sd.c and compare the boot-phase copy path with the Linux-phase path described in the report. Inspect the repeated mmc_spi setup messages and the reported SPI speeds; done would mean identifying and correcting the cause of the severe Linux-phase slowdown, with SD-card copying no longer taking approximately eight hours.

Written by the indexing model from the issue text.